Page 83 - Materials Chemistry, Second Edition

LIFE CYCLE INVENTORY MODELING IN PRACTICE 65

production of sodium hydroxide: diaphragm cell, mercury
cell, and membrane cell. The percentage of European produc-
tion by each technology reported in the ecoinvent database
is different than the U.S. technology mix reported in the U.S.
LCI database. Where possible, the mix of process technologies
should be adjusted to represent the mix relevant to the system
or region being modeled.
Differences in material sourcing. The source or mix of feed-
stock materials used for a process may be different in different
geographic regions. For example, data gathered from U.S. resin
producers for the U.S. LCI Database indicated a different mix
of crude oil and natural gas used as material feedstocks com-
pared to the feedstock mix used by European plastic producers
surveyed for PlasticsEurope's resin modeling [15,16]. In addi-
tion to differences in types and quantities of materials used,
material sourcing differences can also affect the modeling of
material transport distances and modes.
Differences in electricity grids. When using process data from
one region to represent the same process in a different region,
it is important to link process electricity requirements to the
relevant electricity grid for the region where the process is tak-
ing place.

3.6 Conclusion

The science of LCA continues to evolve, encompassing more environmental
flows at increasing levels of detail. The LCI serves as the foundation for the
subsequent impact assessment and interpretation stages of the LCA. In order
for the results and conclusions of the LCA to serve as a basis for sound envi-
ronmental decisions, it is essential that the LCA practitioner stay abreast of
methodological developments and follow accepted LCI methodology and best
practices when conducting the scoping and inventory stages.

References

1. International Organization for Standardization. ISO 14040:2006(E). Environmental manage-
ment - Life cycle assessment - Principles and framework.
2. International Organization for Standardization. ISO 14044:2006(E). Environmental manage-
ment - Life cycle assessment - Requirements and guidelines.
3. Frischknecht, R., Althaus, H.-J., Bauer, C, Doka, G., Heck, T., Jungbluth, N., Kellenberger,
D., and Nemecek, T. 2007. "The environmental relevance of capital goods in life cycle assess-
ments of products and services." Int J Life Cycle Assess.
4. Ecoinvent database. Swiss Centre for Life Cycle Inventories, http://www.ecoinvent.ch/
5. U.S. Environmental Protection Agency (EPA). 1993. Life-Cycle Assessment: Inventory Guidelines
and Principles. EPA/600/R-92/245.